Microwave resonator coupling having two coupling apertures spaced a half wavelength apart

ABSTRACT

Coupling is increased between microwave resonators by providing a plurality of holes in a common wall thereof, the holes being spaced one-half wavelength of the resonant frequency of the resonator.

United States Patent 1 1 3,571,768

Inventor ph C. Gundry [56] References Cited 99 Ariz- UNITED STATESPATENTS 1 PP 2566,386 51 Varian 333/ 1 PM d i -gigs: 2,573,012 51Guttonetal 333/73 [#51 S e 2,749,523 6/l956 aI sss/mw 1 sslgnee q ;t2,879,484 3/1959 'er 333/73 w Primary Examiner- Herman Karl SaalbachAssistant Examiner-T. Vezeau [54] MICROWAVE RESONATOR COU I G HAVINGAttorney-Mueller and Aichele COUPLING APERTURES SP D A HALF ELENGTIIAPART 2 Claims, 2 Drawing Figs.

[52] U.S. CI 83, 333/73, 33 98 [51] Int. Cl "01p 7/06, ABSTRACT:Coupling is increased ween microwave HOlp 1/00, I-IO3b 13/00 resonatorsb oviding a plurality of h s in a comm all [50] Field of Search 333/73,73 thereof, the es being spaced one-half wavelength he (W), 83 resonantfrequency of the resonator.

BACKGROUND This invention relates to coupling between microwaveresonators.

it is known to couple resonators having a common wall by providing ahole at a loop or antinode position in the common wall of theresonators. To increase the coupling, the hole size may be increased.However, upon too great an increase in the size of the hole, the holeitself may have its own resonant frequency, degrading the selectivity ofthe coupled resonators and adding spurious frequency selection.Therefore, by using one hole in a common wall of two resonators,sufficient coupling between the two resonators, as may be required toproduce a broad band filter, is not obtainable without adverse effect onthe frequency selection provided by the resonators.

SUMMARY In accordance with this invention, a plurality of holes areprovided in the common wall of a pair of resonators, the holes beinghalf a wavelength apart. In this manner, sufficient coupling may beprovided between the resonators to provide the required degree ofcoupling and yet no one of the holes needs to be large enough to itselfhave a resonant frequency in a range which can degrade the operation ofthe resultant filtering structure.

DESCRIPTION This invention will be better understood upon reading thefollowing description in connection with the accompanying drawing inwhich:

FIG. 1 is a section of resonators taken through a coupling hole at anangle of 90 with the axes of the coupled resonators, said resonatorsbeing coupled in accordance with this invention; and

HQ. 2 is a section of the coupled resonators of FIG. 1 on line 2-2thereof.

Turning to the two FIGS., a plurality of resonators 10, 12 and 14, and aportion of a resonator 16, are shown. Each resonator is of conductivematerial or of material having conductive surfaces and comprises anouter cylindrical wall 18 and a central post 20 which is shorter thanthe outer wall 18.

The wall 18 and the post 20 are connected by a disclike plate 22. At theresonant frequency of each resonator 10, l2, l4, and 16, the insidesurface of the pate 22 acts as a voltage node and a current antinode.The resonators It), 12, I4, and 16 are arranged as shown in the FIG. tohave a portion of the outer walls 22 of adjacent resonators l0 and l2,l2 and id, and Id and 16 in common. Just above the upper surface of eachplate 22, a hole 24 is provided in the common portion of the wall 18 ofthe adjacent resonators l0, l2, l4, and 16. Also, at a half wavelengthdistance in an axial direction away from the hole 24, that is, atanother current antinode, and also in the common portion of the walls,further holes 26 are provided. Each hole 24 and 26 is small enough sothat it does not in itself, nor do the several holes 24 and 26 together,contribute their own resonances in or near the band of operation of theseveral resonators 10, 12, M, and 16 to degrade the operation of thefilter described. By the use of the two coupling holes 24 and 26 betweeneach of the two adjacent resonators 10, I2, 14, and E6, the couplingbetween the adjacent resonators can be increased to thedesired pointwhereby the resonators l0, E2, 14, and I6 become a band-pass filter. Thewave to be filtered may be applied to the resonator 10 by any knownmeans as by a wire 30 extending into the resonator it) through the hole32 in the outer wall 18 thereof, the wire being connected to the post20.

While a plural hole coupling has been shown and described for resonatorsof the concentric 'type, a similar coupling may be provided forchamber-type resonators having no center post, in which case the insideend of the wire 30 may be left unconnected or may be connected to aninside surface of the resonators. While cylindrical-type resonators havebeen shown and described, other shapes of resonators may be coupled byplural hole coupling as here described. While three resonators areshown, two or more resonators may be provided and may be coupled asdescribed.

I claim: 1. A plurality of coupled resonators: each of said resonatorshaving an outside wall; a portion of the wall of at least two resonatorsbeing in common; there being a plurality of holes in said common wall;and the distance between said holes being equal to a half wavelength ofthe frequency of the said resonators. 2. The invention of claim 1 inwhich said resonators comprise an outside wall and a concentric internalpost.

1. A plurality of coupled resonators: each of said resonators having anoutside wall; a portion of the wall of at least two resonators being incommon; there being a plurality of holes in said common wall; and thedistance between said holes being equal to a half wavelength of thefrequency of the said resonators.
 2. The invention of claim 1 in whichsaid resonators comprise an outside wall and a concentric internal post.